#674: Good to merge after resolving merge conflicts and the following
Address identifier issues from prior call notes.
Defer to nullable changes from other PRs (by @williamdlees).
Enforce snake_case instead of requiring quotes around enums,
except in cases of currently in-use fields, which will require a
version bump to change the enum values.
Require quotes for in-use fields with spaces in enum values.
Regarding v1.4.2 vs v1.5.0, the preference is to leave de-nesting of SubjectGenotype until v2.0.
For iReceptor, only stuff in Subject and Repertoire matter.
Make v1.5.0 milestone and see how many issues it entails.
iReceptor may have to skip support for v1.5.0 if we skip v1.4.2.
Someone (TBD who) will present at the Sept AIRR Event.